Radio frequency identification (“RFID”) systems are used in a variety of applications, including for automated tracking, identifying and authenticating of items. A RFID system typically includes one or more readers (also commonly referred to as interrogators) and RFID tags (also commonly referred to as markers or transponders). Readers are typically positioned at locations where it is desired to control or receive information from the RFID tags that are affixed to items, such as goods, assets, documents or livestock. Reader locations may include entry and/or exit points, inventory control points, or transaction terminals.
The RFID tags may store an identification code having a predefined structure including a header, payload information and a cyclic redundancy code (“CRC”) for error correction. The payload information may include identification information, authentication information or other information, such as sequence instructions for processes or operations that are to be conducted upon an item bearing a selected RFID tag. The data packets may be stored in a memory device within the RFID tag, such as a read only memory (“ROM”) or nonvolatile programmable memory.
Additionally, the RFID tags may support Electronic Product Code (“EPC”), a globally unique serial number that identifies items traveling within a supply chain. The EPC contains information about an item manufacturer, an item type and a specific item serial number. The EPC can also be associated with dynamic data, such as an item origination point or an item production date. The RFID system allows users to perform inquiries using EPC to locate a single instance of an item anywhere within the supply chain.
The data packets are communicated between the RFID tag and the reader over wireless media using a wireless communication device. The RFID tag may be configured as an active RFID tag or a passive RFID tag. Active RFID tags include an energy source, such as a battery, to enable the RFID tag to independently perform operations, such as initiating communication of data packets. Passive RFID tags do not include an energy source and obtain energy from an interrogation signal received from the reader, which enables the RFID tag to initiate communication of the data packets. Active and passive RFID tags are known in the art and are not described further herein.
Conventional RFID architectures include specialized RFID chips having transceivers that include high performance integrated circuit (“IC”) components. These specialized RFID chips are relatively expensive to produce. What is needed is a system and method of providing RFID wireless communications using low cost components. One type of low cost wireless communication device is a packet radio.
Conventional packet radios are deficient because they provide only half duplex operations. Additionally, conventional packet radios are deficient for RFID applications at least because of their limited dynamic range, lack of isolation between the receiver and transmitter and multiplexed or channelized operation. During multiplexed or channelized operation, the transmitter for a conventional packet radio is turned off while it receives a wireless packet transmission. Alternatively, conventional packet radios use different frequencies to transmit and receive data. If the transmitter is not turned off during reception or if the transmitter and receiver fail to operate on different frequencies, the receiver becomes saturated when a high interference signal is generated by the packet radio transmitter. During saturation, the transmitter captures the available receiver dynamic range. To avoid saturation, conventional packet radios either turns off their transmitter when in receive mode or receive signals using a different frequency than the transmitter. What is needed is a system and method of providing full duplex wireless RFID communications using low cost components.